Sharing monitor,keyboard and mouse between 2 pc's

[Ninad Bapat]

Hi
   I have 2 pcs.I will call them as follows 
New PC(N) and old PC (O)
N is a brand new pc with P4.2.4ghz,256mbRAM,40G HDD,D845GVSR mother
board etc. It is triple booting with XP and FC3 and Ubuntu warty
O is a old IBM pc PII 500mhz,64mb ram and CD rom drive. I have
reserved this Pc to load onlu open source software.It is running only
Ubuntu warty
I have connected these 2 with a crossover cable.
However I have only one monitor/keyboard and mouse.

Is there a way by which I can access the desktop of O and issue
commands from N with the help of software.i.e I log in to FC3 on N and
access the Ubuntu desktop of  O and say issue commands run
applications on O

I have heard of some tools but do not know whether they will work or
are suitable for my purpose.foe e.g. Xserver,VNC,nfs

I do not want to buy any special hardware

Thanks and regards 
Ninad